U.S. National Science Foundation
New Home of the UVA Virtual Lab:
We Can Figure This Out.org
University of Virginia
  > WCFTO Home > Energy Home

An Introduction to Sustainable Energy Systems

As individuals, we most often focus upon a single energy technology: One we particularly like (e.g., solar or wind), or one we particularly dislike (e.g., fossil fuel or nuclear).

And then we all start arguing.

At Bell Labs I researched semiconductor devices for fiber optic communications. These were kissing cousins to solar cells, and I got to know a lot of people in the solar cell field (including the founders of two U.S. solar energy companies). So, naturally, for me, that "single energy technology" was solar cells. But for years, my friends told me that "when the cost of cells falls below $X.YZ / Watt, they will take over the world!" And then they fell below that cost. And they did not take over the world. I was clearly missing something. So I began reading almost every article, paper and book on energy I could find. And I eventually figured out what I'd missed: Sustainable energy is not just about the component technologies, it's about how they fit together to create a complete energy system. Put another way, the individual technologies are only pieces of a much larger puzzle. And, frustratingly, many of those pieces still have shapes that are blurred, ill-defined, and/or changing with time.

But why not build an energy system based on just one "piece," for instance solar cells? Because, for now, no single "piece" can affordably produce the amount of energy we need, when we need it. To illustrate, say that solar cell efficiencies suddenly skyrocketed, and costs plummeted. Wouldn't that make an all-solar energy system possible? Yes, but only if you were willing to spend your evenings in the dark, either shivering or sweating. The problem? Solar cells require intense sunlight to produce energy, which only happens (with luck) near midday. But our power consumption peaks in the evenings. So for a solar-based energy system to work, we would also need an effective and affordable way of storing huge quantities of midday energy for many hours - a technology "piece" we do not yet have. Or, if you lived on the U.S. east coast, you might tap into solar cells on the west coast, where the solar peak comes three hours later. But this would require another missing technological piece: efficient and affordable long-distance power transmission lines. So, even with miraculously improved solar cells, we would still need other (miraculously improved) pieces to build an energy system. And without such miracles, it's more likely that we will need many different energy-producing pieces, and many different complementary energy storage/transmission/ . . . pieces.

In my class, and now through this website, we'll examine the science and technology behind those energy "pieces," trying to define at least their present day shapes. But the real goal will be to then use that knowledge to figure out how those pieces might someday complete the "puzzle" of a truly sustainable energy system.

Recommended Textbook:
Sustainable Energy without the Hot Air
David J.C. MacKay
Downloadable for free at: Without the Hot Air.com
Or as a paperback from: UIT Cambridge England, ISBN 978-0-9544529-3-3


Class Notes vs Web Notes?

For my university class, lectures had to be of fixed length and number. That meant that I had to continuously edit and rearrange things as I added new material to the class. On the other hand, because my students were responsible for all class material, the exact order of presentation was not critical. Which freed me to enhance learning by revisiting critical topics multiple times, treating them in increasing depth, weaving them together with related topics.

But this new website is intended as an online resource for you, the citizen-researcher. And you will likely arrive here searching for information on a single specific energy topic. I hope to lure you into broader study. But to facilitate your immediate research, I am rewriting my class notes into what I will call "web notes." For these web notes:

- Material will be reordered so that single topics are mostly covered in a single place (either a single noteset, or consecutive notesets)

- Text descriptions of each noteset will be included in their listing.

- Each noteset will begin with a full outline.

- Notesets will be of whatever length their topic naturally demands.

I expect this rewrite will take me into 2018. This is mostly because, in my classes, I required every student to be a fellow investigator by submitting weekly, midterm, and final exam research papers. And I have thus accumulated a large backlog of new material that I am now anxious to add to this website.

But to pique your interest and provoke your input, I am posting my still incomplete and evolving outline of these new "web notes" below. Please send your suggestions to me via this website's Contact webpage.



Older but Complete Class Notes + Resource Webpages

Lecture Notes


Lecture Notes


Where Do We Go from Here?
(Cap & Trade / Carbon Tax?)


New but still Incomplete Web Notes + Resource Webpages

 My Personal Introduction to Sustainable Energy - New Aug 2017

How and why I became interested / How I learned that full energy systems are almost always required

 U.S. Energy Production and Consumption (resources webpage) - New Sept 2017

Typical household consumption / Total U.S. electrical power production
How this has (or has not) been changing
        The still surprisingly small role of renewables in the U.S.
How states differ in the ways they produce energy
How our consumption varies during the day
        The surprising importance of residential consumption => Follow the money heat!
Worldwide data and maps of per-capita power consumption

 The Science of Electricity: What it is / How it's generated / How we now try to transmit it

Part I: Electric & Magnetic Fields (resources webpage)

Part II: Magnetic Induction: Motors, Generators & Transformers (resources webpage)

 A Generic Electrical Power System

Part I: Power Plants (resources webpage)

The way almost all power plants generate electricity:
        Water + Heat => Steam => Rotary Motion => Electricity
Electricity's near zero "shelf-life" => How we now deal with cycles of energy consumption:
        Base Load vs. Dispatchable Load (vs. Spinning Reserve)
Demonstrating why large-scale energy storage would useful now
But how it will become essential in green energy systems
        With its absence already threatening the growth of such systems
        And/or their stable operation

Part II: The Grid (resources webpage)

Why AC power makes the USE of electricity so much easier:
        How transformers let you pick and choose whatever voltage works best
But why AC power makes DISTRIBUTION of electricity so much more difficult (and inefficient):
        The challenges of synchronization and resistive power loss
        The even bigger challenge of reactive power loss
How to solve this dilemma via clever use of a few electrical devices:
        In the purely AC grids of today
        Or in the sustainable energy AC / DC / AC Grids of tomorrow

 Power from Carbon:

Part I: Conventional Fossil Fuels (resources webpage)

The non-green source of two-thirds of U.S. electrical power
Why combustion of solid > liquid > gas gets progressively more energy efficient (and thus clean)
Coal Power: Conventional vs. IGCC vs. Sequestered IGCC (= so-called "clean coal")
Natural Gas Power: Not so efficient (OCGT) vs. very efficient (CCGT)
Fracking basics / wastewater impact / earthquake potential

Part II: Biomass and Biofuels (resources webpage)

Biomass = Burning of already available organic waste & garbage

Biofuels = Deliberate cultivation of fuel crops
        Their too often abysmal ratio of energy output to net energy input
        Their surprisingly large impact upon the environment & world food prices
        But how they might provide the solution to air transportation's huge carbon footprint

 Hydroelectric Power (resources webpage)

The 2nd biggest "greenish" U.S. energy source (but with #1 - Nuclear - still almost 3X larger!)
The Science of Hydro
Conventional dams and their issues of drought, fish migration, concrete's carbon footprint, (and mercury?)
The alternatives of "Run of the River" and "Pumped Storage Hydro"
The saltwater potential of wave and tidal energy

 Wind Power (resources webpage)

Now growing to challenge Hydro as 2nd biggest green U.S. energy source
The Science of Wind
        The extreme importance of height
        How peak wind speed can be more important than average wind speed
Wind Turbine Technology
Wind Farm Layout
A wind turbine's "capacity" vs. its average energy production
Mismatch in timing between wind energy production vs. consumption =>
        Critical need for wind energy storage
        And for vastly improved power transmission
The importance of location, location, location!
        Offshore wind farms exploiting faster more sustainable winds (plus reduced NIMBY!)
        Growing technology behind offshore wind turbines & possible deep-water floating wind turbines
        Hurricane resistant wind turbines?
Turbines vs. Birds & Bats

 Solar Power:

At present only a bit player in green U.S. energy (with #3 - Wind - 5X larger!)

Part I: Today's Solar Cells (resources webpage)

The critical difference between a mere photoconductor and a true photovoltaic (PV) cell
Optimizing a PV cell: Getting photo electrons & holes to where they need to go
Why that cell will still not efficiently convert sunlight's broad spectrum => the "S-Q limit"
Paralleling earlier discussion of wind energy:
        A solar cell's "capacity" vs. its average energy production
        The importance of location, location, location!
More severe mismatch in timing between solar energy production vs. consumption =>
         Even more critical need for solar energy storage
         And vastly improved power transmission

Part II: Tomorrow's Solar Cells (resources webpage)

How we might beat the S-Q limit of ~30% solar cell efficiency:
        Tandem cells combining cells of different materials
        Quantum Dot cells combing differently sized nano structures
How we might build much less expensive cells:
        Thin film PV cells including perovskites and dyes
How we might instead transform the sun's spectrum to match the cells:
        Luminescent Solar Concentrators (LSCs) for windows
        Conversion of Waste Heat to electricity via metamaterials

Part III: Solar Thermal Power / Solar Thermal Energy Storage

The two types of solar thermal plants:
        Concentrated solar thermal (solar towers) versus
        Distributed solar thermal collectors
Why solar thermal is today's most expensive energy technology
But how solar thermal with built-in energy storage might be a green energy champ:
        Molten salt energy storage
Solar thermal collectors & towers vs. birds & bats

Part IV: Our First Attempts at Affordable Grid-Scale Solar Energy

Photovoltaic farms
        Including California's Topaz plant
Concentrated solar thermal plants:
       California's  Ivanpah and questions raised by omission of energy storage, and bird kills
        Versus Nevada's Crescent Dunes with its built-in energy storage
Distributed solar thermal farms
        Including Morocco's Quarzazate

  Exotic Power Technologies (resources webpage)

Small potential / Unproven: Flying Wind Turbines
Medium potential / Proven but thus far in only exceptionally favorable locations: Geothermal
Large potential / Unproven and hugely expensive: Orbiting Solar Power Stations
Huge potential / Unproven and still elusive after the better part of a century's R&D: Nuclear Fusion

 Electrochemical Energy Storage:

Part I: Today's Batteries (resources webpage)

As seen around the house vs. in electrified transportation vs. for Grid energy storage

Part II: Tomorrow's Batteries / Tomorrow's Fuel Cells

ARPA-E's push for cheaper / more efficient / safer batteries including:
"Saltwater" (aqueous hybrid ion) batteries, solid-electrolyte Li batteries & quinone flow batteries

Fuel cell basics
Fuel cells as enabler of a "hydrogen economy" - or least electrified transportation
But only with radical improvement in their surprisingly poor energy storage efficiency

 Nuclear Energy

Part I: But they blow up! (resources webpage) - Rewritten/Expanded Aug 2017

Fundamental principles of fission reactors & bombs / Three Mile Island, Chernobyl & Fukushima

Part II: Prehistoric Nuclear Reactors? (resources webpage) - Rewritten Aug 2017

Part III: Gen III / III+ Reactors: Confronting Cost & Operational Safety (resources webpage)

AP-1000 / ES-BWR / Small Modular Reactors

Part IV: Gen IV Reactors: Two Designs that Might Radically Reduce Nuclear Waste (resources webpage)

Liquid Fluorine Thorium Reactor / Traveling Wave Reactor

Part V: A Brief Review of Other Gen IV Reactors

 Providing Power Plants with Necessary Land - Especially "Green" Power Plants
 Providing Power Plants with Necessary Water, Fuel and Minerals
 Lifetime Energy Out vs. Energy In => "Energy Return on Investment - EROI" for Competing Technologies
 Power Plant Economics => "Levelized Cost of Energy - LCOE" for Competing Technologies
(with much more to come)



Suggested Energy News Sources:

Copyright: John C. Bean